Larus cachinnans

(last update: February 16, 2013)

Coordinator:
Peter Adriaens (Belgium)
Ies Meulmeester (Netherlands)

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cachinnans plumages

Larus cachinnans 4P45 adult, May-July 2014, Zastów Karczmiski & December 27 2014, Witoszowka Reservoir, Poland. Picture: M. Dabek & Łukasz Bednarz ringing team.

Location: Zastów Karczmiski, Poland - colony at the banks of the Middle Vistula river.
In 2004 240 breeding pairs (95% cachinnans, <5% argentatus). (Ornis Fennica 2011 88, 80-89) and in 2012 592 pairs (90% cachinnans, <10% hybrid / argentatus) and possibly Larus michahellis (pers comm. Łukasz Bednarz).

Middle Vistule river is a location where several taxa breed: see composition. Since this is a mixed breeding population where hybridisation is not uncommon, the ringing centre in Poland decided to label birds "Larus argentatus sensu lato". Still bulk of the breeding birds in Middle Vistula region show features of cachinnans.

below: Larus cachinnans 4P45 adult, May 07 2014, Zastów Karczmiski, Poland. Picture: Łukasz Bednarz ringing team.

Breeding bird trapped at the nest. Adult, with dense speckling in iris. Red orbital ring and gape. No red on upper mandible; black on the upper and black on the lower mandible. Pale yellow legs.
Deep white tongue on P10 (white innerweb breaking the medial band, merged with white tip = thayeri pattern), and single black spot on P5; no black spot on P4. P1 dropped; PMS=1.

below: Larus cachinnans 4P45 adult, July 03 2014, Zastów Karczmiski, Poland. Picture: Łukasz Bednarz ringing team.

Still in the colony, with green 29P1.

below: Larus cachinnans 4P45 adult, December 27 2014, Witoszowka Reservoir, Poland. Picture: M. Dabek.

P10 fully grown.